SLAEDA (3) Linux Manual Page

slaeda.f –

Synopsis

Functions/Subroutines

subroutine slaeda (N, TLVLS, CURLVL, CURPBM, PRMPTR, PERM, GIVPTR, GIVCOL, GIVNUM, Q, QPTR, Z, ZTEMP, INFO)
SLAEDA used by sstedc. Computes the Z vector determining the rank-one modification of the diagonal matrix. Used when the original matrix is dense.

Function/Subroutine Documentation

subroutine slaeda (integerN, integerTLVLS, integerCURLVL, integerCURPBM, integer, dimension( * )PRMPTR, integer, dimension( * )PERM, integer, dimension( * )GIVPTR, integer, dimension( 2, * )GIVCOL, real, dimension( 2, * )GIVNUM, real, dimension( * )Q, integer, dimension( * )QPTR, real, dimension( * )Z, real, dimension( * )ZTEMP, integerINFO)

SLAEDA used by sstedc. Computes the Z vector determining the rank-one modification of the diagonal matrix. Used when the original matrix is dense.

Purpose:

 SLAEDA computes the Z vector corresponding to the merge step in the

 CURLVLth step of the merge process with TLVLS steps for the CURPBMth

 problem.

 

Parameters:

N

 N is INTEGER

 The dimension of the symmetric tridiagonal matrix. N >= 0.

TLVLS

 TLVLS is INTEGER

 The total number of merging levels in the overall divide and

 conquer tree.

CURLVL

 CURLVL is INTEGER

 The current level in the overall merge routine,

 0 <= curlvl <= tlvls.

CURPBM

 CURPBM is INTEGER

 The current problem in the current level in the overall

 merge routine (counting from upper left to lower right).

PRMPTR

 PRMPTR is INTEGER array, dimension (N lg N)

 Contains a list of pointers which indicate where in PERM a

 level’s permutation is stored. PRMPTR(i+1) – PRMPTR(i)

 indicates the size of the permutation and incidentally the

 size of the full, non-deflated problem.

PERM

 PERM is INTEGER array, dimension (N lg N)

 Contains the permutations (from deflation and sorting) to be

 applied to each eigenblock.

GIVPTR

 GIVPTR is INTEGER array, dimension (N lg N)

 Contains a list of pointers which indicate where in GIVCOL a

 level’s Givens rotations are stored. GIVPTR(i+1) – GIVPTR(i)

 indicates the number of Givens rotations.

GIVCOL

 GIVCOL is INTEGER array, dimension (2, N lg N)

 Each pair of numbers indicates a pair of columns to take place

 in a Givens rotation.

GIVNUM

 GIVNUM is REAL array, dimension (2, N lg N)

 Each number indicates the S value to be used in the

 corresponding Givens rotation.

Q

 Q is REAL array, dimension (N**2)

 Contains the square eigenblocks from previous levels, the

 starting positions for blocks are given by QPTR.

QPTR

 QPTR is INTEGER array, dimension (N+2)

 Contains a list of pointers which indicate where in Q an

 eigenblock is stored. SQRT( QPTR(i+1) – QPTR(i) ) indicates

 the size of the block.

Z

 Z is REAL array, dimension (N)

 On output this vector contains the updating vector (the last

 row of the first sub-eigenvector matrix and the first row of

 the second sub-eigenvector matrix).

ZTEMP

 ZTEMP is REAL array, dimension (N)

INFO

 INFO is INTEGER

 = 0: successful exit.

 < 0: if INFO = -i, the i-th argument had an illegal value.

 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Contributors:

Jeff Rutter, Computer Science Division, University of California at Berkeley, USA

Definition at line 166 of file slaeda.f.

Author

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